B. Protein Blotting

A general protocol for sample preparation.

Lyse cells by adding 1X SDS sample buffer (100 µl per well of 6-well plate or 500 µl for a 10 cm diameter plate). Immediately scrape the cells off the plate and transfer the extract to a microcentrifuge tube. Keep on ice.

Western Blot Reprobing Protocol

Reprobing of an existing membrane is a convenient means to immunoblot for multiple proteins independently when only a limited amount of sample is available. It should be noted that for the best possible results a fresh blot is always recommended. Reprobing can be a valuable method but with each reprobing of a blot there is potential for increased background signal. Additionally, it is recommended that you verify the removal of the first antibody complex prior to reprobing so that signal attributed to binding of the new antibody is not leftover signal from the first immunoblotting experiment. This can be done by re-exposing the blot to ECL reagents and making sure there is no signal prior to adding the next primary antibody.

(Optional) To assure that the original signal is removed, wash membrane twice for 5 min each with 10 ml of TBST. Incubate membrane with LumiGLO® with gentle agitation for 1 min at room temperature. Drain membrane of excess developing solution. Do not let dry. Wrap in plastic wrap and expose to x-ray film.

Wash membrane again four times for 5 min each in TBST.

The membrane is now ready to reuse. Start detection at the "Membrane Blocking and Antibody Incubations" step in the Western Immunoblotting Protocol.

NOTE: When using any primary or fluorochrome-conjugated secondary antibody for the first time, titrate the antibody to determine which dilution allows for the strongest specific signal with the least background for your sample.

Source / Purification

Background

Glutamate is the major excitatory neurotransmitter in the mammalian central nervous system. During neurotransmission, glutamate is released from vesicles of the pre-synaptic cell, and glutamate receptors (e.g. NMDA Receptor, AMPA Receptor) bind glutamate for activation at the opposing post-synaptic cell. Excitatory amino acid transporters (EAATs) regulate and maintain extracellular glutamate concentrations below excitotoxic levels. In addition, glutamate transporters may limit the duration of synaptic excitation by an electrogenic process in which the transmitter is cotransported with three sodium ions and one proton, followed by countertransport of a potassium ion. Five EAATs (EAAT1-5) are characterized: EAAT2 (GLT-1) is primarily expressed in astrocytes but is also expressed in neurons of the retina and during fetal development (1). Homozygous EAAT2 knockout mice have spontaneous, lethal seizures and an increased predisposition to acute cortical injury (2). PKC phosphorylates Ser113 of EAAT2 and coincides with glutamate transport (3).